1. Field of the Invention
The present invention relates to a semiconductor processing apparatus. In particular, it relates to a semiconductor processing apparatus that processes a semiconductor wafer while adjusting the temperature thereof.
2. Description of the Related Art
With the recent trend toward higher and higher packaging density of semiconductor devices, circuit patterns are becoming increasingly smaller, and dimension precision requirements are being increasingly severe. With this demand, temperature control of the wafer being processed has become very important. For example, in an etching process in which a high aspect ratio is required, in order to implement anisotropic etching, etching is performed while depositing an organic polymer on the side wall of the part being etched. However, deposition of the organic polymer covering the side wall is varied under the influence of temperature. That is, the temperature of the wafer being processed affects the etch rate or the resulting shape, and if the temperature distribution is non-uniform, the amount of deposited sidewall protective film varies in the surface of the wafer. As a result, there arises a problem in that the resulting shape varies with location in the wafer surface, and the circuit patterns of semiconductor elements cut from the wafer and thus, the performances thereof vary among the elements.
In addition, in recent semiconductor manufacturing processes, wafers with larger diameters are handled, and the plasma, the applied power and the heat input from the apparatus to the wafer are increased. For example, in semiconductor manufacture involving a wafer having a diameter of 300 mm, a bias power in the order of 3 kW is applied to the wafer during the process of etching an interlayer insulating film formed on the wafer. In view of such a circumstance, in a semiconductor manufacturing apparatus, it is technically essential that the temperature of the semiconductor wafer is appropriately controlled in the surface of the wafer during the processing thereof.
In a conventional semiconductor manufacturing apparatus using a plasma, a wafer being plasma-processed is electrostatically stuck to and held on a stage (sample holder) by the action of electrostatic chuck provided on the stage. In addition, in order to assure adequate heat transfer between the wafer and the stage to adjust the temperature of the wafer, a heat conductive gas (typically, helium) is introduced to adjust the temperature of the wafer.
The range of the temperature of the wafer to be adjusted varies with the process. For example, the temperature of the stage that holds the wafer is required to be stably controlled over a wide range from a low temperature of xe2x88x9240xc2x0 C. to a temperature on the order of 100xc2x0 C. during the processing of the wafer. That is, it has become necessary that even if the wafer stage in the plasma processing apparatus is subjected to a significant heat input ranging widely from low temperature to high temperature, an uniform temperature distribution is provided in the surface of the wafer.
In addition, in recent years, demands for non-volatile memories including MRAM and FeRAM have been increased. To etch the materials of these memories, an extremely high temperature of 400xc2x0 C. to 500xc2x0 C. is required. In this case also, since redeposition of a reaction product affects the etching, it is required to properly control the wafer temperature.
As a technique for controlling the temperature of the wafer being processed, there is disclosed a technique in which first and second heat conductive gases are introduced between the wafer and a support for carrying the wafer, and the pressures of the first and second gases are controlled to adjust the heat conduction. In addition, this prior art discloses a technique in which, in order to process the wafer while keeping the temperature thereof constant in the above-described arrangement, an object to be processed for monitoring is used and the temperature distribution in the surface thereof is previously determined, and then, the amounts of the first and second heat conductive gases supplied and discharged via a first and second gas channels are set (for example, see Patent Reference 1).
[Patent Reference 1]
Japanese Patent Laid-Open No. 2002-305188
However, in the prior art described above, in order to provide a desired temperature distribution on the wafer, it is necessary that the amounts of the first and second heat conductive gases supplied and discharged are registered with a control unit of the apparatus. If they are not registered, it is required to separately measure the surface temperature to find a condition that provide the desired temperature distribution, and thus, it disadvantageously takes a long time to determine the processing condition.
For example, it is difficult for the operator who uses the apparatus to predict the temperature of the wafer before starting the processing and accurately set the operation conditions of the apparatus based on the prediction to implement a desired processing.
Thus, if the operator changes an operation condition of the apparatus or a parameter of the etching processing so as to bring the etching characteristics closer to a desired one, the wafer temperature is also changed in accordance with the set condition values or combination thereof, and thus, the desired etching characteristics cannot be attained. Thus, there is a problem in that the precision of the processing of the semiconductor device is degraded.
For example, a case will be described where a target etch rate is not attained and the bias power is increased to 800 W. Here, it is assumed that the temperature of the wafer finally attained after being processed for 60 seconds at 600 W is known from experiment or measurement by the fluorescent thermometer. Since the temperature of the wafer attained when it is processed at a bias power of 800 W is not known, if the wafer is processed under the same condition, the average temperature thereof varies largely. If the temperature varies largely in this way, the temperature affects the resulting etching characteristics, and thus, it is difficult to assess the effect of the changed condition based on comparison with the previously obtained result and to operate the apparatus under the condition that enables precise processing.
Thus, data concerning the He back side gas pressure, the refrigerant temperature, the initial stage temperature and the like that are not changed if the bias power is increased to 800 W are required. However, according to the prior art, the operator who uses the apparatus must find an adequate condition on a trial-and-error basis, so that it may take a long time to find the adequate condition, and thus, the process of setting an adequate condition and starting operation of the apparatus so as to manufacture products with a predetermined performance is degraded in efficiency. In this example, when the He back side gas pressure is set at 1.5 kPa, the average temperature of 82xc2x0 C. is attained finally. However, in general, it is difficult for the operator to predict and set the He back side gas pressure down to the second decimal place, and it takes a long time to predict and set the value.
For example, to obtain precise data, the apparatus is operated plural times under different conditions, such as under different He back side gas pressures of 1.4 kPa, 1.5 kPa and 1.6 kPa. During this operation, it is difficult for the apparatus to perform processing so as to implement desired etching, and the throughput of the semiconductor processing is reduced. Besides, even if the data resulting from a plurality of times of operations is used, extremely large number of operations is required to bring the average value of the temperature of the wafer 1 in a direction parallel to the surface thereof within a narrow range (for example, within xc2x10.5xc2x0 C.). Therefore, the experiment preceding the processing for manufacturing the semiconductor devices to be shipped takes an extremely long time.
A first object of the invention is to provide a semiconductor processing apparatus with an improved operation efficiency.
A second object of the invention is to provide a semiconductor processing apparatus capable of processing a semiconductor wafer with a higher precision.
The above-described objects are attained by providing means, when a semiconductor wafer is processed in a semiconductor processing apparatus, for enabling the temperature of the wafer during the processing to be set. Furthermore, the objects can be attained by determining an operation condition that realizes the set temperature and operating the semiconductor processing apparatus based on the result to process the semiconductor wafer.
More specifically, the above-described objects are attained by a semiconductor processing apparatus that processes a semiconductor wafer mounted therein, comprising: setting means for enabling an user to set a temperature of the semiconductor wafer; and control means for controlling a processing of the semiconductor wafer based on the temperature of the semiconductor wafer set by the setting means.
The above-described objects are attained by a semiconductor processing apparatus that plasma-processes a semiconductor wafer mounted on a stage placed in a container, comprising: setting means for enabling an user to set an temperature of the semiconductor wafer; and control means for controlling an operation of the semiconductor processing apparatus based on information related to the temperature of the semiconductor wafer set by the setting means.
Furthermore, the above-described objects are attained by the semiconductor processing apparatus further having a function of setting an operation condition of the semiconductor processing apparatus based on the set temperature of the wafer.
Furthermore, the above-described objects are attained by the fact that conditions of the operation include at least one of a temperature of a thermal medium that adjusts a temperature of a sample stage on which the semiconductor is mounted, a heater for heating the sample stage, a pressure of a gas introduced between the semiconductor wafer and the sample stage, and a high frequency power applied to the sample stage.
Furthermore, the above-described objects are attained by the semiconductor processing apparatus further comprising: display means for displaying the set operation condition; and input means for enabling the user to input the operation condition.